Infrared telescopes may be ground-based, air-borne, or space telescopes. They contain an infrared camera with a special solid-state infrared detector which must be cooled to cryogenic temperatures. [3]

Ground-based telescopes were the first to be used to observe outer space in infrared. Their popularity increased in the mid-1960s. Ground-based telescopes have limitations because water vapor in the Earth's atmosphere absorbs infrared radiation. Ground-based infrared telescopes tend to be placed on high mountains and in very dry climates to improve visibility.

In the 1960s, scientists used balloons to lift infrared telescopes to higher altitudes. With balloons, they were able to reach about 25 (40 km) miles up. In 1967, infrared telescopes were placed on rockets.[4] These were the first air-borne infrared telescopes. A more recent air-borne infrared telescope to reach the stratosphere was NASA's Stratospheric Observatory for Infrared Astronomy (SOFIA) in May 2010. Together, United States scientists and the German Aerospace Center scientists placed a 17 ton infrared telescope on a Boeing 747 jet airplane.[5]

Placing infrared telescopes in space completely eliminates the interference from the Earth's atmosphere. One of the most significant infrared telescope projects was the Infrared Astronomical Satellite (IRAS) that launched in 1983. It revealed information about other galaxies, as well as information about the center of our galaxy the Milky Way.[6] NASA presently has solar-powered spacecraft in space with an infrared telescope called the Wide-field Infrared Survey Explorer (WISE). It was launched on December 14 in 2009.[7]